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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                   -----------
                                   SCHEDULE TO
                                 AMENDMENT NO. 5

            TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) or 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                                 EON LABS, INC.
                            (Name of Subject Company)

                                   NOVARTIS AG
                              NOVARTIS CORPORATION
                            ZODNAS ACQUISITION CORP.
                       (Name of Filing Persons--Offerors)

                          COMMON STOCK, PAR VALUE $0.01
                         (Title of Class of Securities)

                                    29412E100
                      (CUSIP Number of Class of Securities)

                                  George Miller
                        Head of Legal and General Affairs
                                   Novartis AG
                                 35 Lichtstrasse
                           CH-4002 Basel, Switzerland
                                 41-61-324-1111
            (Name, Address and Telephone Number of Person Authorized
       to Receive Notices and Communications on Behalf of Filing Persons)

                                   -Copies to-
                           Andrew R. Brownstein, Esq.
                             Trevor S. Norwitz, Esq.
                         Wachtell, Lipton, Rosen & Katz
                               51 West 52nd Street
                               New York, NY 10019
                                 (212) 403-1000
                                   -----------

                            CALCULATION OF FILING FEE
     
       Transaction Valuation                  Amount of Filing Fee
------------------------------------------------------------------------
           $977,098,158*                          $115,005*
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------------------------------------------------------------------------

*    Estimated for purposes of calculating the amount of the filing fee only.
     The calculation of the filing fee is described on the cover page to
     Amendment No. 1 to the Schedule TO filed on May 27, 2005.
[X]  Check the box if any part of the fee is offset as provided by Rule
     0-11(a)(2) and identify the filing with which the offsetting fee was
     previously paid. Identify the previous filing by registration statement
     number, or the Form or Schedule and the date of its filing.
      Amount Previously Paid:  $115,005         Filing Party:  Novartis Corp.
      Form or Registration No.:  Schedule TO    Date Filed:  May 23, 2005
[ ]  Check the box if the filing relates solely to preliminary communications
made before the commencement of a tender offer. 
Check the appropriate boxes below to designate any transactions to which the 
statement relates: 
[X]  third-party tender offer subject to Rule 14d-1.
[ ]  issuer tender offer subject to Rule 13e-4. 
[ ]  going-private transaction subject to Rule 13e-3. 
[ ]  amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]
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     This Amendment No. 5 amends and  supplements  the Tender Offer Statement on
Schedule  TO,  as  amended,  (the  "SCHEDULE  TO"),  originally  filed  with the
Securities  and  Exchange  Commission  on  May  23,  2005  and  as  amended  and
supplemented  by  Amendment  No. 1 on May 27, 2005,  Amendment  No. 2 on June 2,
2005,  Amendment  No. 3 on June 7, 2005 and Amendment No. 4 on June 15, 2005, by
Novartis AG, a Swiss Corporation,  Novartis  Corporation  ("NOVARTIS US"), a New
York  corporation  and an indirect  wholly owned  subsidiary of Novartis AG, and
Zodnas  Acquisition  Corp.  ("ZODNAS"),  a Delaware  corporation and an indirect
wholly owned  subsidiary of Novartis US. The Schedule TO relates to the offer by
Zodnas to purchase any and all of the  outstanding  shares of common stock,  par
value $0.01 per share (the "SHARES"),  of Eon Labs, Inc., a Delaware corporation
("EON"),  for $31.00 per  Share,  net to the seller in cash,  upon the terms and
subject to the conditions set forth in the Offer to Purchase, dated May 23, 2005
(the "OFFER TO PURCHASE"),  and in the related Letter of Transmittal.  Copies of
the Offer to Purchase and the related Letter of  Transmittal  are filed with the
Schedule TO as exhibits (a)(1)(A) and (a)(1)(B), respectively. Capitalized terms
used and not defined  herein shall have the meanings  assigned such terms in the
Offer to Purchase and Schedule TO.

ITEMS 1 THROUGH 9 AND 11.

     Items 1 through 9 and 11 of the Schedule TO, which incorporate by reference
the  information  contained  in the Offer to  Purchase,  are hereby  amended and
supplemented as follows:

     On June 21,  2005,  the Offer was  extended  through  5:30 pm New York City
time, on Friday,  July 1, 2005.  Accordingly,  the term "Expiration  Date" means
5:30 pm New York City time on Friday, July 1, 2005, unless we further extend the
period  of time  during  which the Offer  will be open,  in which  case the term
"Expiration  Date" will mean the date at which the Offer,  as so extended,  will
expire.

     The full text of the press release announcing the extension of the Offer as
described above is attached as Exhibit (a)(5)(E) hereto and incorporated  herein
by reference.



ITEM 12.     EXHIBITS

             Item 12 of the Schedule TO is hereby amended by adding thereto
             the following:

(a)(5)(E)    Text of Press Release issued by Novartis dated June 21, 2005.





                                    SIGNATURE

     After due inquiry  and to the best of my  knowledge  and belief,  I certify
that the information set forth in this statement is true, complete and correct.

Dated:  June 21, 2005

                                   NOVARTIS AG


                                   By: /s/ Peter Rupprecht                      
                                      ------------------------------------------
                                      Name      Peter Rupprecht
                                      Title:    authorized signatory


                                   By: /s/ Bruno Heynen                  
                                      ------------------------------------------
                                      Name:     Bruno Heynen
                                      Title:    Authorized Signatory


                                   NOVARTIS CORPORATION


                                   By: /s/ Martin Henrich                       
                                      ------------------------------------------
                                      Name:     Martin Henrich
                                      Title:    Executive Vice President


                                   ZODNAS ACQUISITION CORP.


                                   By: /s/ Wayne P. Merkelson                 
                                      ------------------------------------------
                                      Name:     Wayne P. Merkelson
                                      Title:    Vice President













                                  EXHIBIT INDEX



*(a)(1)(A)   Offer to Purchase, dated May 23, 2005.

*(a)(1)(B)   Form of Letter of Transmittal.

*(a)(1)(C)   Form of Notice of Guaranteed Delivery.

*(a)(1)(D)   Form of Letter to Brokers, Dealers, Commercial Banks, Trust 
             Companies and Other Nominees.

*(a)(1)(E)   Form of Letter to Clients for use by Brokers, Dealers, Commercial 
             Banks, Trust Companies and Other Nominees.

*(a)(1)(F)   Guidelines for Certification of Taxpayer Identification Number
             (TIN) on Substitute Form W-9.

(a)(2)       Not applicable.

(a)(3)       Not applicable.

(a)(4)       Not applicable.

*(a)(5)(A)   Text of Press Release issued by Novartis dated February 21, 2005,
             incorporated in this Schedule TO by reference to the Schedule TO 
             filed by Novartis AG, Novartis US and Zodnas on February 22, 2005.

*(a)(5)(B)   Form of Summary Advertisement published in The Wall Street Journal 
             on May 23, 2005.

*(a)(5)(C)   Text of Press Release issued by Novartis dated May 27, 2005.

*(a)(5)(D)   Text of Press Release issued by Novartis dated June 7, 2005.

(a)(5)(E)    Text of Text of Press Release issued by Novartis dated June 21, 
             2005.

*(a)(6)(A)   Complaint titled Ellen Wiehl v. Eon Labs, Inc. et al., filed on
             February 22, 2005, in the Chancery Court of the State of Delaware, 
             County of New Castle.

*(a)(6)(B)   Complaint titled Paulena Partners LLC v. Eon Labs, Inc. et al., 
             filed on February 22, 2005, in the Chancery Court of the State of 
             Delaware, County of New Castle.

*(a)(6)(C)   Complaint titled Robert Kemp, IRRA v. Eon Labs, Inc. et al., filed 
             on February 22, 2005, in the Chancery Court of the State of 
             Delaware, County of New Castle.





*(a)(6)(D)   Complaint titled Peter J. Calcagno v. Eon Labs, Inc. et al., filed 
             on February 23, 2005, in the Chancery Court of the State of 
             Delaware, County of New Castle.

*(a)(6)(E)   Complaint titled Christopher Pizzo v. Novartis AG et al., filed on 
             February 23, 2005, in the Supreme Court of the State of New York, 
             County of New York.

*(a)(6)(F)   Complaint titled Erste Sparinvest Kapitalanlagegesellschaft MBH v.
             Eon Labs, Inc. et al., filed on March 1, 2005, in the Chancery 
             Court of the State of Delaware, County of New Castle.

*(a)(6)(G)   Complaint titled Merl Huntsinger v. Eon Labs, Inc. et al., filed on
             March 1, 2005, in the Chancery Court of the State of Delaware, 
             County of New Castle.

*(a)(6)(H)   Complaint titled Jason Hung v. Eon Labs, Inc. et al., filed on 
             March 3, 2005, in the Chancery Court of the State of Delaware, 
             County of New Castle.

*(a)(6)(I)   Consolidated Amended Complaint titled In re Eon Labs, Inc.
             Shareholders Litigation, filed on May 27, 2005, in the Chancery 
             Court of the State of Delaware, County of New Castle.

(b)          None.

*(d)(1)      Agreement and Plan of Merger, dated as of February 20, 2005, by and
             among Novartis US, Zodnas, Eon and, for purposes of Section 12 
             thereof only, Novartis AG, incorporated in this Schedule TO by 
             reference to Exhibit 2.2 to the Schedule 13D filed by Novartis US, 
             Novartis AG and Zodnas on March 2, 2005.

*(d)(2)      Agreement for Purchase and Sale of Stock, dated as of February 20, 
             2005, by and between Novartis US, Santo and, for purposes of 
             Section 10.12 thereof only, Novartis AG, incorporated in this 
             Schedule TO by reference to Exhibit 2.1 to the Schedule 13D filed 
             by Novartis US, Novartis AG and Zodnas on March 2, 2005.

*(d)(3)      Confidentiality Agreement, by and between Novartis US and Eon,
             dated as of February 11, 2005, incorporated in this Schedule TO by 
             reference to Exhibit 2.3 to the Schedule 13D filed by Novartis US, 
             Novartis AG and Zodnas on March 2, 2005.

(g)          None.

(h)          Not applicable.

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* Previously filed.